This article presents a vector algorithm of the solution of the Helmholtz equation by beam propagation method (BPM), based on representation of calculations in the single instruction, multiple data model. Use of this algorithm on the graphic NVIDIA GeForce GTX 660Ti processor on the compute unified device architecture technology results in 30-times acceleration of calculations in comparison with calculations on the Intel Core2 Duo CPU E8500.
The fabrication of diamond-based optical elements for high-power CO2 lasers is of particular interest because of the low optical absorption coefficient of this material in combination with its very high thermal conductivity and the weak temperature dependence of refractive index. Recent advances in gas-phase synthesis have made it possible to fabricate polycrystalline CVD diamond films (DF) whose optical and thermal properties are close to those of single crystal diamond material, whereas they are far cheaper. As a result, these sophisticated materials are applied more and more to tasks dominated till now by other materials. Such examples for this are windows for high-power CO2 lasers in the 5 - 20 kW domain1 and beam-splitters2. Recently new techniques have been proposed for antireflective structuring of DF surface3,4 as well as for generation of phase microrelief to manufacture diamond diffractive optical elements (DOEs) for the far IR range5-8, 10. The realisation of DOE by UV-laser ablation has been considered 5-8. Using of ion-chemical etching9 and plasma etching10 is considered later. The present paper is devoted to further development of considered approaches5,9. The realization of diamond diffractive optical elements (DOEs) is considered, able to focus an incoming CO2 laser beam into certain pregiven focal domains. Results of experimental investigation of designed DOEs are presented and discussed.
In the proposed work, the well-known FDTD method is considerably updated. A new approach taken to the formulation of radiation conditions allows a considerable enhancement of the modeling accuracy to be achieved, compared with the widely used TF/SF technique.
Recently a new technique has been proposed for laser-assisted generation of phase microrelief to manufacture diamond diffractive lenses for the far IR range. In the present paper the realization of diamond diffractive optical elements (DOEs) is considered, able to focus an incoming CO2 laser beam into certain pregiven focal domains. Exemplarily, two completely different DOEs for different tasks of laser beam focusing have been designed by different methods, manufactured and finally investigated by means of optical experiment and computer simulation. Measured intensity distributions in the DOEs' focal planes as well as measured diffraction efficiencies have been compared with related results of computer simulation, and have been found to be in good mutual concordance. Obtained first results indicate that technique of laser-assisted ablation can be effectively used for manufacturing of high quality diamond DOEs for laser beam focusing.
Recently a new technique has been proposed for laser-assisted generation of phase microrelief to manufacture diamond diffractive lenses for the far IR range. In the present paper the realization of diamond diffractive optical elements (DOEs) is considered, able to focus an incoming CO2 laser beam into certain pregiven focal domains. Exemplarily, two completely different DOEs for different tasks of laser beam focusing have been designed by different methods, manufactured and finally investigated by means of optical experiment and computer simulation. Measured intensity distributions in the DOEs’focal planes as well as measured diffraction efficiencies have been compared with related results of computer simulation, and have been found to be in good mutual concordance. Obtained first results indicate that technique of laser-assisted ablation can be effectively used for manufacturing of high quality diamond DOEs for laser beam focusing.
Advances in numerical methods and progress in the computer hardware made possible numerical solution of Maxwell's equations. Thus, imposing adequate boundary conditions and substituting into the equations medium parameters enables the simulation of light propagation in various media. We developed difference schemes making it possible to model optical processes that occur when various types of light waves travel through optical elements, such as diffractive lenses and antireflecting gratings.
Laser light modes are beams in whose cross-section the complex amplitude is described by eigenfunctions of the operator of light propagation in the waveguide medium. The fundamental properties of modes are their orthogonality and their ability to retain their structure during propagation for example in a lens-like medium, in free space or a Fourier stage. Novel Diffractive Optical Elements (DOEs) of MODAN-type open up new promising potentialities of solving the tasks of generation, transformation, superposition and subsequent separation again of different laser modes. Now we present new results obtained by synthesis and investigation of beams consisting of more than one two-dimensional Gaussian laser modes with the same value of propagation constant formed by DOEs. The exploitation of these phenomena could enhance the fiber optical system transfer capacity without pulse enlargement.
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